1. Field of the Invention
The present invention relates to a method for preparing aluminum-containing crystalline zeolites having the IFR structure (xe2x80x9cIFR zeolitexe2x80x9d) using a zeolite as an active source of aluminum oxide.
2. State of the Art
IFR zeolites are known. U.S. Pat. No. 5,437,855, issued Aug. 1, 1995 to Valyocsik, discloses a zeolite, designated xe2x80x9cMCM-58xe2x80x9d, having the IFR structure prepared using a benzylquinuclidinium organic directing agent. However, it does not disclose the use of a zeolite as a source of aluminum for MCM-58. U.S. Pat. No. 5,441,721, issued Aug. 15, 1995 to Valyocsik, also discloses MCM-58, but prepared using a benzyltropanium organic directing agent. Use of a zeolite as the source of aluminum for MCM-58 is not disclosed. It has been discovered that when a zeolite (Na-Y) is used as the source of aluminum and benzyltropanium is used as the structure directing agent, the only zeolite produced was FAU (a starting material). No zeolite with the IFR structure was made (see Comparative Example B below). Both patents are incorporated by reference herein in their entirety. U.S. Pat. No. 5,653,956, issued Aug. 5, 1997 to Zones, discloses a zeolite, designated SSZ-42, prepared using an organic templating agent selected from the group consisting of 1-benzyl-4-aza-1-azonia-bicyclo [2.2.2] octane cations and N-benzyl-1-azabicyclo[2.2.2]octane cations. The SSZ-42 may contain oxides of boron, aluminum, gallium, iron or titanium, but at least 50% of those oxides must be boron oxide. Zeolites are disclosed as a possible source of aluminum or boron (see col. 8). In Example 14, an aluminum-containing SSZ-42 is made, but the aluminum is added to the SSZ-42 by post-treatment after the boron-containing SSZ-42 was prepared. Likewise, in Example 16 a boron- and gallium-containing SSZ-42 is made by adding gallium by post-treatment of previously made SSZ-42. In Example 20, an aluminum- and boron-containing (50/50) SSZ-42 is prepared directly using sodium borate as the source of boron and sodium aluminum trihydrate as the source of aluminum. U.S. Pat. No. 5,653,956 is incorporated herein by reference in its entirety.
U.S. Pat. No. 5,340,563, issued Aug. 23, 1994 to Zones et al., discloses an improved method for preparing large pore zeolites. The method involves preparing a reaction mixture containing a source zeolite, an alkali metal, nitrogen containing organic cation, a source of silica and water. The source zeolite contains sodalite substructures and has a tetrahedra atom density of less than about 15 TO2 per 1000 Angstroms3. Examples of zeolites prepared by this method are SSZ-25, SSZ-31, SSZ-37, beta and ZSM-12. Zeolites A, N-A, ZK-4, faujasite, X, Y, ZK-5 and rho are disclosed as source zeolites. U.S. Pat. No. 5,340,563 is incorporated by reference herein in its entirety.
U.S. Pat. No. 4,503,024, issued Mar. 5, 1985 to Bourgogne et al., discloses synthesizing zeolites using zeolites as reactants. It does not, however, disclose the synthesis of a zeolite having the IFR structure.
In accordance with the present invention there is provided a method for preparing a zeolite having the IFR structure comprising:
(a) preparing a reaction mixture comprising (1) a zeolite which is an active source of aluminum oxide, (2) an active source of alkali metal oxide, (3) an active source of an oxide of a tetravalent element, and (4) an organic template selected from the group consisting of a N-benzyl-1,4-diazabicyclo[2.2.2] octane cation and a N-benzyl quinuclidinium cation, wherein said reaction mixture has a composition in terms of mole ratios of oxides falling within the following ranges:
YO2/Al2O3 about 5 to about 100
OHxe2x88x92/YO2 about 0.05 to about 0.50
Q/YO2 about 0.10 to about 1.0
M2/n/YO2 about 0.005 to about 0.50
H2O/YO2 about 3 to about 100
Q/Q+M2/n about 0.50 to about 0.95
wherein Y is silicon, germanium or mixtures thereof, Q is an 1-benzyl-4-aza-1-azonia bicyclo[2.2.2]octane cation or N-benzyl quinuclidinium cation, M is an alkali metal cation or alkaline earth metal cation and n is the valence of M; and (b) maintaining the reaction mixture under conditions sufficient to form crystals of the IFR zeolite.
Also provided in accordance with the present invention is an essentially boron-free zeolite having a composition, as synthesized and in the anhydrous state, in terms of mole ratios as follows:
YO2/Al2O3 about 5 to about 100
OH31/YO2 about 0.05 to about 0.50
Z/YO2 about 0.10 to about 1.0
M2/n/YO2 about 0.005 to about 0.50
H2O/YO2 about 3 to about 100
Z/Z+M2/n about 0.50 to about 0.95
wherein Y, M and n are as defined above and Z is a 1-benzyl-4-aza-1-azonia bicyclo[2.2.2]octane cation.
Further provided in accordance with the present invention is a zeolite having the IFR crystal structure and having a composition, as synthesized and in the anhydrous state, in terms of mole ratios as follows:
YO2/Al2O3 about 5 to about 100
YO2/B2O3 about 5 to about 100
OHxe2x88x92/YO2 about 0.05 to about 0.50
Z/YO2 about 0.10 to about 1.0
M2/n/YO2 about 0.005 to about 0.50
H2O/YO2 about 3 to about 100
Z/Z+M2/n about 0.50 to about 0.95
wherein Y, M, and n are as defined above and Z is a 1-benzyl-4-aza-1-azonia-bicyclo[2.2.2]octane cation and wherein the amount of aluminum is greater than the amount of boron.